By now my views on Pi Day are well documented (see earlier posts from 2011 and 2009 if you’re curious). Recently, though, I’ve decided to try to be a little less curmudgeonly when it comes to math holidays. Consequently, while it would be easy to provide snarky commentary on articles with particularly egregious mathematical errors, this year I will try to restrain myself.

As I’ve said before, one of my biggest problems with Pi day is that the activities are, for the most part, a little ridiculous, and don’t actually do anything to better the general populace’s understanding of mathematics. Last year, I explained why contests involving the recitation of digits of are silly, so this year I’d like to offer an alternative. Why not use the day as an opportunity to debate with students the relative merits of and ?

Last year marked the dawn of a new era in mathematical holidays. Spearheaded by Dr. Michael Hartl, Tau Day (celebrated today, June 28th) is an attempt to draw awareness to what he sees as a fundamental error in the definition of the beloved circle constant . In particular, he (and others) argue that the more natural choice of the circle constant should be , which he affectionately dubs . I outlined the reasons for this in a post last year, though if you have the time, I highly encourage you to read Hartl’s Tau Manifesto.

This year, I thought it would be nice to talk with Dr. Hartl in more detail about his inspirations for Tau Day, and where he envisions it in the future. He was gracious enough to agree to a brief interview, which I humbly submit to you here.